The Arizona sentinel., 1887-12-03
CONCERNING OUDS,
Their Nature, Forms, Iomposition, Y
lOcity, Height, Etc.

| the atmosphere. III IL rests upon the
surface of the earth we call it fog
We sec amass of vapor on the sum-
NIT of high mountain and we caH
it cloud, but if we climb to the top Of
the mountain and find ourselves in the
cloud we see it to be simply fog. To
our observation. clouds take on forms
that are almost infinite in variety,
yet they may be divided into six
classes, each presenting quite distinct
characteristics. These are known as
cirrus, cumulus and stratus cloud, as
simple divisions; and cirro- cumulus,
cirro-stratus and cumulo-stratus as
compound divisions. TIL, cirrus
cloud consists of long, slender. fila
ments, either parallel or diverging
from each other. These clouds have
the greatest elevation and the least
density of all clouds. Even in fair
weather the sky is seldom free from
small distant groups of cirrus clouds.
They are thought 10 b. made up of
spicul8 of ice or flakes of snow, since
at the great height at which
they float, from five to eight miles
above the earth. the temperature of
the air is below freezing point even in
midsummer The cumulus cloud is
much denser than the cirrus, and is
formed nearer the earth. 1t usually
has the form of a hemispherical or
convex mass with horizontal base.
This is the cloud often seen in large
masses near the horizon, looking like
huge mountains of snow. The round
ed top of this cloud results from the
mode of its formation. As the earth
is heated by the suns rays. currents
of warm air rise, carrying with them
invisible vapor. When they reach a
certain height this vapor is condensed
and forms cloud, and since the upward
motion is greater under the center of
the cloud, the vapor is then carried to
its greatest height. The stratus cloud
is widely-extended, horizontal sheet.
often covering the entire sky, and
and hanging so low that it frequently
touches the earth's surface in the
form of fog. For the compound
notifications of cloud forms, the cir
ro-cumulus is seen in small rounded
masses, often very near together o.
account of their feecy appearance
these are often called 'woolly clouds.
This cloud IS ve"y frequex. in sr.r----e,.
but seldom precedes rain. The cir11-
stratus consists Of fibrous clou Is
spread out in strata, which are
either horizontal or slightly -
clined 10 the horizen. Sometimes the
whole sky is mottled with the cloud,
looking like the back of a mackerel,
and, therefore, is callel a mackerel
sky. This cloud always presagcs wind
and rain. The cumulo-stratus is the
large dark cloud formed is ttiiio mass
ing of the fcecF cumalus in great
heaps. These clouds arc TO be seen in
great magnificence on the approach of
a thunderstorm, an are, therefore.
often called thunder heads. Some
meteoroIogists also classify with the
above the nimbus cloud, 'rhicu 5
stratus cloud from which rain is ia.l-
ing, but others do not think it worth
while to keep this division. The
height of n cloud is measured by
rigononctrical rule by observing its
direction simultaneously ut two sta
tions. In mountainous countries it
can be compared with the peaks near
which it passes. Most accurate re-
ct1lf OH o1 lr-o
ing in balloon and noting the height
of the barometer when entering the
cloud and again when emerging from
it, the barometer giving the means of
computing corresponding attitudes.
The height of clouds is very variable
The stratus, as we have said, often
descending to the earth. In pleasant
weather the lower limit of cumulus
clouds varies from 5000 to 5000 feet
elevation, and their upper limit from
1000 to u, 900 feet. Cirrus clouds never
descend Eelow the summit of Mount
Blanc, which has a height of Is, IA
feet, and are often seen to be far above
mountains that are % o01 10 %. 900
feet high. ig is estimated however
,hat they would not be visible at
height exeaadirc ten u-i'es. I- verii-
cal thickness clouds are supposed to
seldom exceed HaIi q mile. but the
enormous masses Of eUmulus are
sometimes estimated at over three
miles. Clouds move with the wind,
and there IS no way ofestimating their
movement but by me assuring the
velocity of the wind currents. Clouds
reflect light, of course, or they would
not be visible; such light as can pass
through them is refracted out of its
path by the presence of the vapor
particles. Thus, when we see objects
through fog we often notice that
they are distant from their true posi-
ton or unnaturally magnified. The
effect of clouds on heat is 10 lessen it,
the water particles absorbing it, and
lowering the temperature of the air by
their conversion into invisible vapor
Nevertheless, clouds hanging low in
cold weather prevent fall Of tenn
perature by preventing the radiation
Of heat from the earth's surface. As
to moisture. clouds are, obviously,
moisture itself as we'll as its cause
Chicago Inter- Ocean,
"A Buffalo inventor will soon make |
n public test of an odd-looking street
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